This invention relates to an apparatus which roughens the sides of surfaced lumber to give it the appearance of rough-sawn lumber, and in particular to such an apparatus which processes all four sides of the lumber simultaneously.
When lumber is made it first is cut with a saw to a size which is slightly larger than its ultimate size, and it then is surfaced with a planer, which brings it to its final dimensions. In some building applications it is aesthetically desirable to maintain the rough sawn surface texture created by sawing, and for this reason unfinished lumber is sold as rough-sawn lumber. However, this lumber is slightly larger than comparable sizes of surfaced lumber which creates alignment problems when rough-sawn and surfaced lumber is used on different sections of a structure. As a result a demand has arisen for rough-sawn lumber which has surfaced lumber dimensions.
While it certainly is possible for a lumber mill to rough saw lumber in surfaced lumber sizes, there is insufficient demand for this to be done on a regular basis. Furthermore, stocking a complete inventory of both surfaced and rough-sawn lumber would require a significant increase in storage space at all levels of distribution. Accordingly, lumber has heretofore only been sawn to surfaced lumber sizes on special order, and this is economically feasible only when large quantities of lumber are required. On smaller jobs it is necessary to resaw rough-sawn lumber to surfaced lumber dimensions, which is expensive and difficult to accomplish since all four sides must be sawn independently and each cut must be at an extremely shallow depth.
The subject invention overcomes these problems by providing an apparatus which roughens all four sides of surfaced lumber in a single pass without materially altering its dimensions and is adjustable to readily accommodate various lumber sizes. This is accomplished by mounting endless loop chains, having roughening teeth projecting from them, on a plurality of sleds which are supported on a common frame. The endless chains are supported by guide assemblies which position the roughening teeth so that they project through slots which are defined in planar faces of the sleds. Preferably, the guide assemblies are adjustable so that the roughening teeth can be centered in the slot, and the depth of cut can be adjusted. Motors drive the chains so that the roughening teeth translate across the slots and roughen the sides of a piece of lumber which is transported past the sleds.
A first pair of the sleds is positioned side by side with one another with their faces oriented vertically. One of the first sleds is fixedly attached to the frame and the other first sled is slidable on the frame relative to the fixed first sled. Thus, the distance between the faces of the first sleds can be adjusted so that the face of one of the first sleds is adjacent to each of the side surfaces of a piece of lumber as it is passed between them. A second pair of the sleds has its faces oriented horizontally. The second pair of sleds also contains both a fixed and slidable sled so that the sleds can be adjusted to contact the top and bottom surfaces of the piece of lumber as it is transported between them.
Once the sleds are adjusted so that their faces are aligned with all four sides of a piece of lumber, the lumber is inserted into the device and a transport mechanism transports it past the sleds where the roughening teeth roughen its sides. In the preferred embodiment the transport mechanism includes two pinch roller assemblies with one being located on each side of the sleds. Each pinch roller assembly includes a pair of pinch rollers which are rotatable on vertically spaced-apart horizontal axes. The upper roller in each pair is movable relative to the lower roller. Thus, the rollers can be adjusted so that a piece of lumber will be squeezed between them. The rollers in each pair are driven in synchronous counter rotation by a motor to move the lumber through the apparatus.
The lower pinch rollers are aligned with the fixed second sled and lumber guides mounted on the faces of the sleds index the piece of lumber so that it is in alignment with both fixed sleds. Support rollers associated with the second sleds carry the lumber as it is passed between the second sleds in order to prevent it from dragging on the faces and creating friction.
Accordingly, it is a principal object of the present invention to provide an apparatus which will create a rough-sawn texture on all four sides of a piece of surfaced lumber in a single pass.
It is a further object of the present invention to provide such an apparatus which can easily be adjustable to accommodate different size lumber.
It is a further object of the present invention to provide such an apparatus in which the cutting element can easily be adjusted to set the depth of cut.
It is a still further object of the present invention to provide such an apparatus which is an integral self-contained unit.
The foregoing and other objectives, features and advantages of the present invention will be more readily understood upon consideration of the following detailed description of the invention taken in conjunction with the accompanying drawings.